Date: Tue, 28 Feb 2006 11:23:34 +0200 From: Danny Braniss <danny@cs.huji.ac.il> To: Tom Samplonius <tom@uniserve.com> Cc: freebsd-scsi@freebsd.org Subject: Re: Qlogic fibre channel support questions Message-ID: <E1FE14w-0001r7-QO@cs1.cs.huji.ac.il> In-Reply-To: Your message of Mon, 27 Feb 2006 22:53:07 -0800 (PST) .
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> On Mon, 27 Feb 2006, Matthew Jacob wrote:
>
> > Okay- let me ask why diskless booting doesn't work for you?
>
> Because NFS is slow. A locally disk (or a SAN attached disk, which is
> essentially the same to FreeBSD) is going to be faster than NFS, no matter what.
don't be too hasty with conclusions :-)
1- diskless: you can always boot diskless, then switch to 'real disk'
in /etc/fstab:
/dev/da0a / ufs rw 1 1
or what we do:
/dev/da0b none swap sw
/dev/da0d /var ufs rw 2 2
/dev/da0h /home ufs rw 2 2
so you don't have to boot from the SAN, but after loading the kernel
(via 'slow' NFS) it will use the SAN.
2- as to speed, it all depends, specially on how deep are your pockets.
i've been running several 'benchmarks' latetly and disk speed is not
everything.
sample:
host is a Sun Fire X4200 (dual dula core Opteron) with SAS disks
OS is FreeBSD 6.1-PRERELEASE amd64.
make buildworld:
diskless: 40m16.71s real 54m18.55s user 17m54.69s sys
(using only 1 server*)
nondiskless: 20m51.58s real 51m13.19s user 12m59.84s sys
" but /usr/obj is iSCSI:
28m23.29s real 52m17.27s user 14m23.06s sys
" but /usr/src and /usr/obj is iSCSI:
20m38.20s real 52m10.19s user 14m48.74s sys
diskless but /usr/src and /usr/obj is iSCSI:
20m22.66s real 50m56.14s user 13m8.20s sys
*: server in this case is a Xeon running in 64 mode but not very fast
ethernet - em0 at 1gb but at about 50% efficiency.
this server will 'make buildworld' in about 40 min. using the onboard
LSILogic v3 MegaRAID RAID0.
[iSCSI target is a Network Appliance]
sorry for the noise,
danny
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